I have just started hearing a slight "marble rattle" noise at times from the engine compartment of my Cavalier only when the car is moving and in gear. When the engine is running but the car is at rest or if the car is coasting with the clutch depressed or just in neutral, the noise is not present. It is a 2.2 / 5 speed manual model that I have put about 100,000 miles on since I bought it.
I think the transmission or clutch may be suspect as to where the noise is coming from because of when the noise is present or not present as I stated.
And the noise lasts only a second or two on acceleration in just about any of the gears and then it appears to go away at crusing speeds.
I've never had a problem with the transmission or clutch before and have had very few troubles with the car at all, so I'd like to get to the heart of the problem asap.
Does anyone have experience with this? Any suggestions?

 

throw out bearing maybe?

 

Hmm, almost forgot I posted this question in the first place!

Thanks for the suggestion. I can't rule out a throw-out bearing, but I can't prove it either. It's a mysterious thing for sure. The rattle comes and goes and right now I can't really hear it. I've put thousands of miles on it since it started and nothing seems the worse for wear.